## Dire Splitting Enhancements

The Dire parton shower allows to weight individual splittings to allow efficient isolation and study of their impact. This can e.g. be used to increase the rate of a single splitting, and/or decrease the rate of others, thus e.g. allowing to study rare splittings. It should be noted that this can make some splittings much more frequent, at the expense of a new event weight, whose fluctuations might require larger event samples.

Nevertheless, sometimes enhancements can be useful. Dire offers the option to enhance each available splitting kernel separately. For brevity, we here only describe auxiliary parameters, then one enhancement factor, and then just list all other corresponding keywords.

`parm` Enhance:pTmin (`default = -1.0`)
The minimal pT value t (in GeV) of emissions below which no enhancement of emission probabilities is applied. Negative values mean that enhancements may be applied to emissions at any pT. Default value is -1.0 GeV.

`parm` Enhance:Dire_fsr_qcd_1->1&21 (`default = 1.0`)
The (double) value with which the final-state q->qg splitting is enhanced. Note that the enhancement is compensated by an additional weight factor included in the parton shower weight, to guarantee the correct real-emission and no-emission probabilities are generated.

### QCD splittings

`parm` Enhance:Dire_fsr_qcd_1->21&1 (`default = 1.0`)
(FSR, q -> g q)

`parm` Enhance:Dire_fsr_qcd_21->21&21a (`default = 1.0`)
(FSR, g -> g g, 1st color structure)

`parm` Enhance:Dire_fsr_qcd_21->21&21b (`default = 1.0`)
(FSR, g -> g g, 2nd color structure)

`parm` Enhance:Dire_fsr_qcd_21->1&1a (`default = 1.0`)
(FSR, g -> q qbar, soft quark)

`parm` Enhance:Dire_fsr_qcd_21->1&1b (`default = 1.0`)
(FSR, g -> q qbar, soft antiquark)

`parm` Enhance:Dire_fsr_qcd_1->2&1&2 (`default = 1.0`)
(FSR, q -> q' q qbar')

`parm` Enhance:Dire_fsr_qcd_1->1&1&1 (`default = 1.0`)
(FSR, q -> qbar q qbar)

`parm` Enhance:Dire_fsr_qcd_1->1&21_notPartial (`default = 1.0`)
(FSR q -> q g, with full soft logarithms, as e.g. needed in radiation off top decay products)

`parm` Enhance:Dire_fsr_qcd_21->21&21_notPartial (`default = 1.0`)
(FSR g -> g g, with full soft logarithms, as e.g. needed in radiation off top decay products)

`parm` Enhance:Dire_fsr_qcd_21->1&1_notPartial (`default = 1.0`)
(FSR g -> q qbar, with full soft logarithms, as e.g. needed in radiation off top decay products)

`parm` Enhance:Dire_fsr_qcd_1->1&21&21 (`default = 1.0`)
(FSR q -> q g g)

`parm` Enhance:Dire_fsr_qcd_1->1&d&dbar (`default = 1.0`)
(FSR q -> q d dbar, soft quark)

`parm` Enhance:Dire_fsr_qcd_1->1&dbar&d (`default = 1.0`)
(FSR q -> q d dbar, soft antiquark)

`parm` Enhance:Dire_fsr_qcd_1->1&u&ubar (`default = 1.0`)
(FSR q -> q u ubar, soft quark)

`parm` Enhance:Dire_fsr_qcd_1->1&ubar&u (`default = 1.0`)
(FSR q -> q u ubar, soft antiquark)

`parm` Enhance:Dire_fsr_qcd_1->1&s&sbar (`default = 1.0`)
(FSR q -> q s sbar, soft quark)

`parm` Enhance:Dire_fsr_qcd_1->1&sbar&s (`default = 1.0`)
(FSR q -> q s sbar, soft antiquark)

`parm` Enhance:Dire_fsr_qcd_1->1&c&cbar (`default = 1.0`)
(FSR q -> q c cbar, soft quark)

`parm` Enhance:Dire_fsr_qcd_1->1&cbar&c (`default = 1.0`)
(FSR q -> q c cbar, soft antiquark)

`parm` Enhance:Dire_fsr_qcd_1->1&b&bbar (`default = 1.0`)
(FSR q -> q b bbar, soft quark)

`parm` Enhance:Dire_fsr_qcd_1->1&bbar&b (`default = 1.0`)
(FSR q -> q b bbar, soft antiquark)

`parm` Enhance:Dire_fsr_qcd_21->21&21&21 (`default = 1.0`)
(FSR g -> g g g)

`parm` Enhance:Dire_fsr_qcd_21->21&d&dbar (`default = 1.0`)
(FSR g -> q d dbar, soft quark)

`parm` Enhance:Dire_fsr_qcd_21->21&dbar&d (`default = 1.0`)
(FSR g -> g d dbar, soft antiquark)

`parm` Enhance:Dire_fsr_qcd_21->21&u&ubar (`default = 1.0`)
(FSR g -> g u ubar, soft quark)

`parm` Enhance:Dire_fsr_qcd_21->21&ubar&u (`default = 1.0`)
(FSR g -> g u ubar, soft antiquark)

`parm` Enhance:Dire_fsr_qcd_21->21&s&sbar (`default = 1.0`)
(FSR g -> g s sbar, soft quark)

`parm` Enhance:Dire_fsr_qcd_21->21&sbar&s (`default = 1.0`)
(FSR g -> g s sbar, soft antiquark)

`parm` Enhance:Dire_fsr_qcd_21->21&c&cbar (`default = 1.0`)
(FSR g -> g c cbar, soft quark)

`parm` Enhance:Dire_fsr_qcd_21->21&cbar&c (`default = 1.0`)
(FSR g -> g c cbar, soft antiquark)

`parm` Enhance:Dire_fsr_qcd_21->21&b&bbar (`default = 1.0`)
(FSR g -> g b bbar, soft quark)

`parm` Enhance:Dire_fsr_qcd_21->21&bbar&b (`default = 1.0`)
(FSR g -> g b bbar, soft antiquark)

`parm` Enhance:Dire_isr_qcd_1->1&21 (`default = 1.0`)
(ISR q -> q g)

`parm` Enhance:Dire_isr_qcd_21->1&1 (`default = 1.0`)
(ISR g -> q qbar)

`parm` Enhance:Dire_isr_qcd_21->21&21a (`default = 1.0`)
(ISR g -> g g, soft quark)

`parm` Enhance:Dire_isr_qcd_21->21&21b (`default = 1.0`)
(ISR g -> g g, soft antiquark)

`parm` Enhance:Dire_isr_qcd_1->21&1 (`default = 1.0`)
(ISR q -> g q)

`parm` Enhance:Dire_isr_qcd_1->2&1&2 (`default = 1.0`)
(ISR q -> q' q qbar')

`parm` Enhance:Dire_isr_qcd_1->1&1&1 (`default = 1.0`)
(ISR q -> qbar q qbar)

### QED splittings

`parm` Enhance:Dire_fsr_qed_1->1&22 (`default = 1.0`)
(FSR q -> q a)

`parm` Enhance:Dire_fsr_qed_1->22&1 (`default = 1.0`)
(FSR q -> a q)

`parm` Enhance:Dire_fsr_qed_11->11&22 (`default = 1.0`)
(FSR l -> l a)

`parm` Enhance:Dire_fsr_qed_11->22&11 (`default = 1.0`)
(FSR l -> a l)

`parm` Enhance:Dire_fsr_qed_22->1&1a (`default = 1.0`)
(FSR a -> d dbar, soft quark)

`parm` Enhance:Dire_fsr_qed_22->1&1b (`default = 1.0`)
(FSR a -> d dbar, soft antiquark)

`parm` Enhance:Dire_fsr_qed_22->2&2a (`default = 1.0`)
(FSR a -> u ubar, soft quark)

`parm` Enhance:Dire_fsr_qed_22->2&2b (`default = 1.0`)
(FSR a -> u ubar, soft antiquark)

`parm` Enhance:Dire_fsr_qed_22->3&3a (`default = 1.0`)
(FSR a -> s sbar, soft quark)

`parm` Enhance:Dire_fsr_qed_22->3&3b (`default = 1.0`)
(FSR a -> s sbar, soft antiquark)

`parm` Enhance:Dire_fsr_qed_22->4&4a (`default = 1.0`)
(FSR a -> c cbar, soft quark)

`parm` Enhance:Dire_fsr_qed_22->4&4b (`default = 1.0`)
(FSR a -> c cbar, soft antiquark)

`parm` Enhance:Dire_fsr_qed_22->5&5a (`default = 1.0`)
(FSR a -> b bbar, soft quark)

`parm` Enhance:Dire_fsr_qed_22->5&5b (`default = 1.0`)
(FSR a -> b bbar, soft antiquark)

`parm` Enhance:Dire_fsr_qed_22->11&11a (`default = 1.0`)
(FSR a -> e+ e-, soft e-)

`parm` Enhance:Dire_fsr_qed_22->11&11b (`default = 1.0`)
(FSR a -> e+ e-, soft e+)

`parm` Enhance:Dire_fsr_qed_22->13&13a (`default = 1.0`)
(FSR a -> mu+ mu-, soft mu-)

`parm` Enhance:Dire_fsr_qed_22->13&13b (`default = 1.0`)
(FSR a -> mu+ mu-, soft mu+)

`parm` Enhance:Dire_fsr_qed_22->15&15a (`default = 1.0`)
(FSR a -> tau+ tau-, soft tau-)

`parm` Enhance:Dire_fsr_qed_22->15&15b (`default = 1.0`)
(FSR a -> tau+ tau-, soft tau+)

`parm` Enhance:Dire_fsr_qed_1->1&22_notPartial (`default = 1.0`)
(FSR q -> q a, with full soft logarithms, as e.g. needed in radiation off top decay products)

`parm` Enhance:Dire_fsr_qed_11->11&22_notPartial (`default = 1.0`)
(FSR l -> l a, with full soft logarithms, as e.g. needed in radiation off top decay products)

`parm` Enhance:Dire_isr_qed_1->1&22 (`default = 1.0`)
(ISR q -> q a)

`parm` Enhance:Dire_isr_qed_1->22&1 (`default = 1.0`)
(ISR q -> a q)

`parm` Enhance:Dire_isr_qed_22->1&1 (`default = 1.0`)
(ISR a -> q qbar)

`parm` Enhance:Dire_isr_qed_11->11&22 (`default = 1.0`)
(ISR l -> l a)

`parm` Enhance:Dire_isr_qed_11->22&11 (`default = 1.0`)
(FSR l -> a l)

`parm` Enhance:Dire_isr_qed_22->11&11 (`default = 1.0`)
(FSR a -> l+ l-).

### Electroweak splittings

At present, electroweak evolution is under development, so that these settings should not be touched for production for now.

`parm` Enhance:Dire_fsr_ew_1->1&23 (`default = 1.0`)
(FSR q -> q z)

`parm` Enhance:Dire_fsr_ew_1->23&1 (`default = 1.0`)
(FSR q -> z q)

`parm` Enhance:Dire_fsr_ew_23->1&1a (`default = 1.0`)
(FSR z -> q qbar, soft quark)

`parm` Enhance:Dire_fsr_ew_23->1&1b (`default = 1.0`)
(FSR z -> q qbar, soft antiquark)

`parm` Enhance:Dire_fsr_ew_24->1&1a (`default = 1.0`)
FSR w -> q qbar', soft quark)

`parm` Enhance:Dire_fsr_ew_24->1&1b (`default = 1.0`)
(FSR w -> q qbar', soft antiquark).

`parm` Enhance:Dire_fsr_ew_24->24&22 (`default = 1.0`)
(FSR w -> w a).

`parm` Enhance:Dire_fsr_ew_25->21&21 (`default = 1.0`)
(FSR h -> g g, as e.g. needed for Higgs hypothesis testing).

`parm` Enhance:Dire_fsr_ew_25->22&22 (`default = 1.0`)
(FSR h -> a a, as e.g. needed for Higgs hypothesis testing).

### Dark U(1) splittings

At present, dark photon evolution is under development, so that these settings should not be touched for production for now.

`parm` Enhance:Dire_fsr_u1new_1->1&22 (`default = 1.0`)
(FSR q -> q aDark)

`parm` Enhance:Dire_fsr_u1new_1->22&1 (`default = 1.0`)
(FSR q -> aDark q)

`parm` Enhance:Dire_fsr_u1new_11->11&22 (`default = 1.0`)
(FSR l -> l aDark)

`parm` Enhance:Dire_fsr_u1new_11->22&11 (`default = 1.0`)
(FSR l -> aDark l)

`parm` Enhance:Dire_fsr_u1new_22->1&1a (`default = 1.0`)
(FSR aDark -> d dbar, soft quark)

`parm` Enhance:Dire_fsr_u1new_22->1&1b (`default = 1.0`)
(FSR aDark -> d dbar, soft antiquark)

`parm` Enhance:Dire_fsr_u1new_22->2&2a (`default = 1.0`)
(FSR aDark -> u ubar, soft quark)

`parm` Enhance:Dire_fsr_u1new_22->2&2b (`default = 1.0`)
(FSR aDark -> u ubar, soft antiquark)

`parm` Enhance:Dire_fsr_u1new_22->3&3a (`default = 1.0`)
(FSR aDark -> s sbar, soft quark)

`parm` Enhance:Dire_fsr_u1new_22->3&3b (`default = 1.0`)
(FSR aDark -> s sbar, soft antiquark)

`parm` Enhance:Dire_fsr_u1new_22->4&4a (`default = 1.0`)
(FSR aDark -> c cbar, soft quark)

`parm` Enhance:Dire_fsr_u1new_22->4&4b (`default = 1.0`)
(FSR aDark -> c cbar, soft antiquark)

`parm` Enhance:Dire_fsr_u1new_22->5&5a (`default = 1.0`)
(FSR aDark -> b bbar, soft quark)

`parm` Enhance:Dire_fsr_u1new_22->5&5b (`default = 1.0`)
(FSR aDark -> b bbar, soft antiquark)

`parm` Enhance:Dire_fsr_u1new_22->11&11a (`default = 1.0`)
(FSR aDark -> e+ e-, soft e-)

`parm` Enhance:Dire_fsr_u1new_22->11&11b (`default = 1.0`)
(FSR aDark -> e+ e-, soft e+)

`parm` Enhance:Dire_fsr_u1new_22->13&13a (`default = 1.0`)
(FSR aDark -> mu+ mu-, soft mu-)

`parm` Enhance:Dire_fsr_u1new_22->13&13b (`default = 1.0`)
(FSR aDark -> mu+ mu-, soft mu+)

`parm` Enhance:Dire_fsr_u1new_22->15&15a (`default = 1.0`)
(FSR aDark -> tau+ tau-, soft tau-)

`parm` Enhance:Dire_fsr_u1new_22->15&15b (`default = 1.0`)
(FSR aDark -> tau+ tau-, soft tau+)

`parm` Enhance:Dire_fsr_u1new_22->211&211a (`default = 1.0`)
(FSR aDark -> pi+ pi-, soft pi-)

`parm` Enhance:Dire_fsr_u1new_22->211&211b (`default = 1.0`)
(FSR aDark -> pi+ pi-, soft pi+)

`parm` Enhance:Dire_isr_u1new_1->1&22 (`default = 1.0`)
(ISR q -> q aDark)

`parm` Enhance:Dire_isr_u1new_1->22&1 (`default = 1.0`)
(ISR q -> aDark a)

`parm` Enhance:Dire_isr_u1new_22->1&1 (`default = 1.0`)
(ISR aDark -> q qbar)

`parm` Enhance:Dire_isr_u1new_11->11&22 (`default = 1.0`)
(ISR l -> l aDark)

`parm` Enhance:Dire_isr_u1new_11->22&11 (`default = 1.0`)
(ISR l -> aDark l)

`parm` Enhance:Dire_isr_u1new_22->11&11 (`default = 1.0`)
(ISR aDark -> l+ l-).